Bottom Line:
The results of this study show that leaves treated with calcium channels inhibitors (verapamil) or calcium chelators (oxalate and EGTA) are impaired in ROS production.These data further extend our knowledge on the connection between wounding, calcium influx and ROS production.Moreover they provide for the first time the evidence that, following wounding, calcium changes precede a burst in ROS in the same location.

Background: Wounded leaves of Arabidopsis thaliana produce reactive oxygen species (ROS) within minutes after wounding and become resistant to the pathogenic fungus Botrytis cinerea at a local level. This fast response of the plants to the wound is called wound-induced resistance (WIR). However the molecular mechanisms of this response and the signal cascade between the wound and ROS production are still largely unknown. Calcium is a conserved signal and it is involved in many abiotic stress responses in plants, furthermore, calcium pathways act very fast.

Results: The results of this study show that leaves treated with calcium channels inhibitors (verapamil) or calcium chelators (oxalate and EGTA) are impaired in ROS production. Moreover, leaves treated with verapamil, EGTA or oxalate were more susceptible to B. cinerea after wounding. The intracellular measurements of calcium changes indicated quick but transient calcium dynamics taking place few seconds after wounding in cells neighbouring the wound site. This change in the cytosolic calcium was followed in the same region by a more stable ROS burst.

Conclusions: These data further extend our knowledge on the connection between wounding, calcium influx and ROS production. Moreover they provide for the first time the evidence that, following wounding, calcium changes precede a burst in ROS in the same location.

Mentions:
A distinctive feature of WIR is that wounded A. thaliana leaves become resistant to the necrotrophic fungus B. cinerea[5]. Thus, we tested if verapamil and chelating agents affected WIR to B. cinerea. Droplets of tested molecules were applied on leaves and after 3 hours, droplets were removed, leaves were wounded and suspensions of B. cinerea spores were placed on the wound sites. After 3 days of incubation, the wounded control was fully protected while unwounded water-treated controls displayed the typical symptoms of B. cinerea infection (necrosis at the infection site) (Figure 2). Similar to their effect on wound-induced ROS formation, verapamil (starting at 1 mM), EGTA (starting at 10 mM) and oxalate (starting at 10 mM) all affected WIR (Figure 2). Plants treated with oxalate and EGTA without wounding showed an enhanced lesion size, indicating a possible involvement of calcium in the basal resistance (Figure 2). Taken together, these results indicate that calcium might be involved in the pathway that couples perception of wounding with the induction of ROS and WIR.

Mentions:
A distinctive feature of WIR is that wounded A. thaliana leaves become resistant to the necrotrophic fungus B. cinerea[5]. Thus, we tested if verapamil and chelating agents affected WIR to B. cinerea. Droplets of tested molecules were applied on leaves and after 3 hours, droplets were removed, leaves were wounded and suspensions of B. cinerea spores were placed on the wound sites. After 3 days of incubation, the wounded control was fully protected while unwounded water-treated controls displayed the typical symptoms of B. cinerea infection (necrosis at the infection site) (Figure 2). Similar to their effect on wound-induced ROS formation, verapamil (starting at 1 mM), EGTA (starting at 10 mM) and oxalate (starting at 10 mM) all affected WIR (Figure 2). Plants treated with oxalate and EGTA without wounding showed an enhanced lesion size, indicating a possible involvement of calcium in the basal resistance (Figure 2). Taken together, these results indicate that calcium might be involved in the pathway that couples perception of wounding with the induction of ROS and WIR.

Bottom Line:
The results of this study show that leaves treated with calcium channels inhibitors (verapamil) or calcium chelators (oxalate and EGTA) are impaired in ROS production.These data further extend our knowledge on the connection between wounding, calcium influx and ROS production.Moreover they provide for the first time the evidence that, following wounding, calcium changes precede a burst in ROS in the same location.

Background: Wounded leaves of Arabidopsis thaliana produce reactive oxygen species (ROS) within minutes after wounding and become resistant to the pathogenic fungus Botrytis cinerea at a local level. This fast response of the plants to the wound is called wound-induced resistance (WIR). However the molecular mechanisms of this response and the signal cascade between the wound and ROS production are still largely unknown. Calcium is a conserved signal and it is involved in many abiotic stress responses in plants, furthermore, calcium pathways act very fast.

Results: The results of this study show that leaves treated with calcium channels inhibitors (verapamil) or calcium chelators (oxalate and EGTA) are impaired in ROS production. Moreover, leaves treated with verapamil, EGTA or oxalate were more susceptible to B. cinerea after wounding. The intracellular measurements of calcium changes indicated quick but transient calcium dynamics taking place few seconds after wounding in cells neighbouring the wound site. This change in the cytosolic calcium was followed in the same region by a more stable ROS burst.

Conclusions: These data further extend our knowledge on the connection between wounding, calcium influx and ROS production. Moreover they provide for the first time the evidence that, following wounding, calcium changes precede a burst in ROS in the same location.